1. Field of the Invention
This invention pertains to the field of lubricants, especially greases.
2. Description of the Prior Art
It is desirable in the selection of greases to consider the environment that the greases will have to operate under and in many cases, to select a grease which has properties which will allow it to perform adequately where two surfaces come together with considerable force. This force makes it very difficult to keep a lubricant in place and prevent the two surfaces from actually touching each other. A lubricant between these surfaces must possess a property known as extreme pressure (EP) tolerance. This property allows a lubricant to continue to lubricate the two surfaces even though the bulk of the grease is forced out from between the surfaces. The art has many references to additives which impart extreme pressure properties to greases. It was surprising, however, to discover that a particular combination of additives imparted synergistic extreme pressure properties to greases. That is, the extreme pressure properties of the resulting grease having the combination of additives as disclosed by applicant, are superior to greases containing only one or two components of the proposed three component additive combination. By using the additive combination disclosed hereinafter, a grease may be obtained which has unexpectedly superior extreme pressure properties.